WordPress Pages or Posts?

I've nearly decided to use WordPress to implement our company's intranet. I'm thinking that I'll use the key/value meta facility to assign content to groups, and then add some http authentication to provide selective visibility to that content by group. What I can't quite decide it whether to use "Pages" for content, or categorized "Posts".

If you have any ideas, opinion, experience with this, I'd love to hear about it.

PS: I considered MediaWiki, but found it a bit cumbersome to work with.